The invention relates to motor vehicle suspensions, and in particular, to the category of axles having two suspension arms, one end of which bears a stub axle for receiving a wheel and the other end being coupled on the body of the vehicle by means of a shaft, and further having a crossmember joining the two suspension arms, and whose main element, providing a "suspension spring" function, is a torsion-stressed resilient joint. Patent application WO 97/47486 describes an axle of this kind.
One of the advantages of using elastomeric flexible joints serving as suspension springs in pivot bearings of the axle on the body of the vehicle is to facilitate greater integration of vibration or shock spring absorption or filtering functions. Depending on the specifications to be satisfied for the different vehicles, this type of axle can make it possible to reduce the total number of parts used, notably, because separate filtering blocks are used, such are commonly used for coupling the axles or suspension arms to the body. Such elastomeric blocks have become universal and have supplanted the use of ball-bearings, for they are capable of providing the degree of freedom required, while ensuring good filtering favorable to comfort, notably on the acoustic level. Furthermore, such filtering blocks can be provided with rather elaborate guiding functions controlling their deformation under working stresses in order to make, for example, autodirectional axles, that is, axles which slightly steer the wheels under the sole effect of load transfers.
In the case of elastomeric joints, such as those used to couple suspension arms to the body, their contribution to takeup of the load is negligible (in the order of one percent). In fact, their contribution to takeup of the load, which is low and inherent, absolutely does not influence the sizing of the joint. If it is sought to make a real contribution to takeup of the load with such joints, adding to such joints the function of a suspension spring, one finds that it becomes difficult to preserve their customary filtering properties. Thus, a true concentration in the same element of suspension spring and filtering functions appears problematical.